DVP-ES2-EX2-SS2-SA2-SX2-Operation Manual

4. Communications
Exception
code:
Explanation:
01
Illegal command code:
The command code received in the command message is invalid for PLC.
02
Illegal device address:
The device address received in the command message is invalid for PLC.
03
Illegal device content:
The data received in the command message is invalid for PLC.
07
1. Checksum Error
- Check if the checksum is correct
2. Illegal command messages
- The command message is too short.
- Length command message is out of range.
4.3 Communication Protocol RTU mode
Communication Data Structure
9600 (Baud rate), 8 (data bits), EVEN (Parity), 1 (Start bit), 1 (Stop bit)
START
Address
Command code
DATA (n-1)
…….
DATA 0
CRC CHK Low
CRC CHK High
END
No data input ≥ 10 ms
Communication Address: the 8-bit binary address
Command Code: the 8-bit binary address
Data Contents:
n × 8-bit BIN data, n≦202
CRC Checksum:
The 16-bit CRC checksum is composed of 2 8-bit binary codes
No data input ≥ 10 ms
4.3.1 Address (Communication Address)
Valid communication addresses are in the range of 0~254. Communication address equals to 0 means
broadcast to all PLCs. PLC will not respond to a broadcast message. PLC will reply a normal message
to the master device when communication address is not 0.
Example, communication address should be set to 10 (Hex) when communicating with a PLC with
address 16 (Dec) (16 in Decimal = 10 in Hex)
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